Contrary to popular belief, many Microchiropteran bats can see as well as echolocate. In earlier studies, R. Suthers and I demonstrated that bats can discriminate patterns and detect and avoid obstacles in flight visually as well as acoustically. The problems of sensory integration, therefore, are quite real for these animals. Localization of objects in three-dimensional space and tracking of moving objectives (or localizing stationary objects when oneself is moving) are also critical tasks for bats. In cats, all three functions, localization, tracking, and integration of visual and auditory information, are performed by the superior colliculus. In bats the role of the superior colliculus is unknown. I propose to test the effect of superior colliculus ablation on the ability of Microchiroptera to avoid large, visible obstacles. Animals will be flown pre- and post-operatively in the deaf, blind, and deaf-blind conditions with appropriate controls for experience, fatigue and motor deficits. The effects of ablation on a relatively large-eyed species with faint echolocation, Carollia perspicillata or Phyllostomus hastatus, will be compared to the effects on a strong echolocator, Myotis lucifugus, whose vision is poor. The significance of the study is twofold. First, though the auditory neurophysiology of echolocating bats has been studied for fifteen years, the possible role of the superior colliculus has been ignored. Second, the problems of sensory integration and of cross-modal transfer are important problems for bats and such studies may elucidate basic mechanisms used by other mammals including man.